(1) Field of the Disclosure
This invention relates generally to the field of electronic circuits and relates in particular to relaxation oscillators.
(2) Description of the Background
A relaxation oscillator is an oscillator based upon the behavior of a physical system's return to equilibrium after being disturbed. That is, a dynamical system within the oscillator continuously dissipates its internal energy. Normally the system would return to its natural equilibrium; however, each time the system reaches some threshold sufficiently close to its equilibrium, a mechanism disturbs it with additional energy. Hence, the oscillator's behavior is characterized by long periods of dissipation followed by short impulses. The period of the oscillations is set by the time it takes for the system to relax from each disturbed state to the threshold that triggers the next disturbance.
It is a challenge for designers of CMOS relaxation oscillators to design circuits, which require minimal chip area, a reliable duty cycle, and a low minimum frequency.